The controller realized what had happened, and asked the aircraft, "Aircraft X, verify heading 200." The aircraft responded, "Negative, we are heading 297 direct ZZZ." The controller then asked if the aircraft could maintain its own terrain and obstacle clearance, because he was now in an area with a 3700 feet
minimum vectoring altitude. The pilot responded, "Affirmative." The aircraft was then issued its clearance and after reaching 3700 feet was cleared as filed.
When off airways, ATC will issue clearances and permit direct routings only if the airplane is in radar contact and the airplane is at or above the
minimum vectoring altitude (MVA), the lowest altitude where controllers have reliable radar coverage.
In the U.S., controllers keep pilots away from obstacles using
minimum vectoring altitudes (MVA, used mainly by approach controls) or minimum instrument altitudes (MIA, used by centers).
Controllers may be aware of some of those for their airspace, but the one they're most keenly familiar with is the MVA, or
Minimum Vectoring Altitude. I mentioned it briefly before, but what is it exactly?
The pilot was asked to confirm he was in VMC and ATC advised the
minimum vectoring altitude for the area was 5500 feet msl.
The MVA is the
Minimum Vectoring Altitude for TRACON controllers.
Minimum Vectoring Altitude (MVA) is the lowest MSL altitude where air traffic controllers can be reliably expected to have all aircraft visible on radar in a given local area.
At this point, a pilot flying a VCOA procedure would probably be on top of the airport skirting the bases of the clouds, probably below the
minimum vectoring altitude and nowhere near an airway.
In cases where you're flying in a radar environment, ATC may be able to descend you down to what's called a
minimum vectoring altitude, which can be lower.
After we locate the pilot's IFR flight plan, we then ensure that he's at a safe IFR altitude by verifying he's above our
minimum vectoring altitude (MVA) or asking him "Can you maintain your own terrain and obstruction clearance?" from his present altitude up to our MVA.
Normally, the intermediate segment is at least five miles long, but it can be cut down to three, and if the ceiling isn't lower than 500 feet above the
minimum vectoring altitude and the visibility at the airport (or from a Pirep) is at least three miles, it can be even less.
I was cleared to descend to 12,500 feet, the
minimum vectoring altitude in that area.